Sun-tracker
In solar cell array applications and solar instrumentation, it is desirable to monitor the approximate position of the sun to allow efficient automatic alignme...
Light-level-detector
If R, the sensor matching resistor, is equal to the "dark" resistance of the cadmium sulfide cell, the amplifier output will range from 0 to "" 2 as the lightl...
Optical-sensor-to-ttl-interface
This circuit is designed to detect a low light level at the sensor, amplify the signal, and provide a TTLlevet output. When the optical sensor detects low-leve...
Low-light-level-drop-detector
This self-biasing configuration is useful any time srnall changes in light level must be detected, for example, when monitoring very low flow rates by counting...
Flame-monitor
Monitoring a flame and directly switching a 120-V load is easily accomplished using the Ll4G1 for point sources of light. For light sources which subtend over ...
Thermocouple-preamplifier
The MAX420 is operated at a gain of 191 to convert the 52 p.VI o C output of the type J thermocouple to a 10 mV/°C signal. The -2.2 mV/°C tempco of the...
Strain-gauge-instrumentation-amplifier
This circuit has an overall gain of 320. More gain can easily be obtained by lowering the value of R2. Untrimmed Vas is 10 11V. and Vas tempco is less· than...
Simple-ir-detector
This simple IR detector turns on a real LED when Q2 is exposed to invisible IR radiation found in fiber-optics systems, position sensors, and TV remote-control...
Long-range-object-detector
When long ranges must be worked with IR light sources, and when high system reliability is required, pulsed-mode operation of the IRis required. Additional rel...
Low-cost-humidity-sensor
The sensor is an RC oscillator in which, a water-absorbent plastic film is the insulator in the capacitive element. The capacitance of the film increases with ...
Hall-effect-compass
The TL3103 linear Hall-effect device can be used as a compass. By definition, the north pole of a magnet is the pole that is attracted by the magnetic north ...
Hall-effect-switches
Hall-effect switches have several advantages over mechanical and optically coupled switches, They"re insensitive to environmental light and dirt, they don"t bi...
Gas-smoke-detector
In the presence of smoke or gas, the ac output voltage increases and becomes rectified, filtered and zener-diode coupled (D2 for thresholding) to sensitivity c...
Smoke-detector
This smoke detector uses a MEM 817 p-channel enhancement mode MOSFET as its buffer amplifier. Operation of the sensor is based on a decrease in the current whe...
Gas-smoke-detector
The sensor is based on the selective absorption of hydrocarbons by an n-type metal-oxide surface. The heater in the device serves to burn off the hydrocarbons ...
Smoke-gas-vapor-detector
Transformer T1 supplies power to the heater of the sensor. Since the sensor is fairly sensitive to heater voltage, diodes Da, D4, and D5 regulate the heater vo...
Liquid-level-monitor
This monitor uses a common 7 41 amp configured as a comparator and a low cost nontransistor as an output driver. With no liquid detected, a voltage of about ...
Liquid-level-checker
Although many circuits use the varying-capacitance method for checking liquid levels, this simple resistive circuit is much easier to construct. Even a tank of...
Soil-moisture-meter
ICl, an Intersil ICL 7106, contains an aid converter, a 3,1/2-digit LCD driver, a clock, a voltage reference, seven segment decoders, and display drivers. A si...
Dual-liquid-level-detector
Uses CA3410 quad BiMOS op amp to sense small currents. Because the op amp"s input current is low, a current of only 1 p.A passing through the sensor will chang...